1. Field of Invention
The present invention relates to reverse (or peripheral) sensing system, and more particularly to a reverse sensing system displaying an overhead view of a region around a vehicle (or “overhead vehicle image”).
2. Related Art
Unexpected events of the cars when traveling often occur due to carelessness of the drivers, visual dead angle, or variation of external environment. Along with the development of the electronic information technique, many researchers are devoted themselves to develop a parking assist system incorporating a powerful operation capability of a trip computer and an image-capturing technique, so as to alert the drivers before the accidents, thereby effectively assisting the drivers during traveling. The parking assist system (e.g. a common reverse sensing system) senses a distance to an impediment behind the vehicle by the use of an ultrasonic sensor, and the approach of the impediment is notified by a sound with different volumes and frequencies. With the popularization of the image sensors, some of the reverse sensing systems may further shoot the real scene image for the drivers to intuitively sense a space relation between the vehicle and the impediment around the vehicle. The low skill drivers use the parking assist system when parking, so as to prevent colliding with the impediment around the vehicle to cause damages of the vehicle.
However, the reverse sensing system providing the image shot behind the vehicle still has defects. FIG. 1A is a schematic view of reversing the vehicle, and FIG. 1B is a schematic view of the scene image shot by the reverse sensing system of the prior art. Referring to FIGS. 1A and 1B, for example, the driver intends to park a vehicle 110 before a parking line in front of a wall 120. When the reverse of the vehicle 110 starts, the reverse sensing system shoots the scene behind the vehicle, and displays the shot image on a screen of the reverse sensing system. However, due to the dead angle of shooting, the impediment 140 behind the vehicle 110 cannot be displayed in the shot image. For example, the impediment 140 in FIG. 1A cannot be displayed in the image of FIG. 1B. When the driver just relies on the shot image to reverse the vehicle, the vehicle may collide with the impediment 140 to cause damages of the vehicle. Some reverse sensing systems shoot the scene images from different angles and positions, and switch between the scene images at different angles and positions to assist the drivers when reversing the vehicles. However, the switching between the scene images attracts the driver's attention, such that the driver cannot concentrate on driving.